CN110823926B - Method for detecting quality of complex steel plate shear wall node based on ground penetrating radar scanning - Google Patents
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Abstract
A method for detecting the quality of a complex steel plate shear wall node based on ground penetrating radar scanning belongs to the technical field of reinforced concrete structure construction, and aims to obtain an identification method based on an amplitude attribute rule by researching an amplitude parameter value corresponding to a radar image single-channel waveform. The method comprises the following steps: setting parameters aiming at the special detection object of the complex steel plate shear wall node; arranging a survey line according to the requirement of the optimal scanning effect, and controlling the moving speed of the radar antenna; further processing and analyzing the extracted numerical value by using MATLAB programming, determining the geometric characteristic of the target body according to the intersection of the energy interval and the variance interval, and determining the dielectric property of the target body according to the sum of all amplitude absolute values in the intersection region; and obtaining an evaluation index of the construction quality of the complex node of the steel plate shear wall according to the geometric characteristics and the dielectric properties of the target body. The invention has the advantages of simple and efficient detection, convenient operation, cost saving, accurate identification, no damage, no pollution and the like.
Description
Technical Field
The invention belongs to the technical field of reinforced concrete structure construction, and particularly relates to a method for detecting the construction quality of a complex steel plate shear wall node based on ground penetrating radar scanning.
Background
The steel plate shear wall node is used as a complex node in a super high-rise building structure, the stress and the reinforcement are complex, and the reinforcement condition of the node and the pouring effect of concrete in site construction have great influence on whether the node has a good functional state within the design service life. In a super high-rise building structure, more complex nodes are arranged, and the stress and reinforcement arrangement conditions of all the nodes are different, so that for the important complex nodes which are poured, the detection of the actual reinforcement arrangement condition inside the complex nodes and the pouring effect of concrete is difficult. In order to obtain accurate information inside the complex-structure node, nondestructive detection is carried out on the poured important complex node by adopting a ground penetrating radar.
The radar method is a conventional geophysical detection method, electromagnetic waves emitted by an antenna are transmitted in a concrete member, and the defects of the position of a steel bar, the thickness of a protective layer, void, incompact and the like in the concrete structural member can be detected according to the dielectric constant difference of different substances. The method comprises the steps of firstly emitting electromagnetic waves to concrete through a radar emitting antenna, generating reflected electromagnetic waves when the electromagnetic waves encounter an interface with different electromagnetic properties, then receiving the reflected electromagnetic waves through a receiving antenna to obtain a corresponding radar section image and a radar oscillogram, and obtaining defect characters or steel bar positions and the like in the concrete by utilizing the oscillogram obtained by continuous multipoint sampling. When the difference of the electromagnetic properties of the medium in the concrete member is larger, the generated reflected wave signal is stronger, and the detection effect is better. When the quality of the concrete is evaluated, the concrete quality can not be only evaluated by using the strength index, and the lining quality and the construction quality of the concrete can be comprehensively and comprehensively evaluated by considering factors such as the condition of reinforcing steel bars, the lining thickness of the concrete, the compactness, the void and the like.
Disclosure of Invention
The invention aims to provide a method for detecting the construction quality of a complex steel plate shear wall node based on ground penetrating radar scanning.
The invention adopts the following technical scheme:
a method for detecting the quality of a complex steel plate shear wall node based on ground penetrating radar scanning comprises the following steps:
firstly, adopting a 1700Hz radar antenna, setting the dielectric constant to be 7, selecting 10ns for a time window, setting the number of sampling points to be 512, selecting a ranging mode to scan, setting the distance between ranging wheels to be 60mm, setting the gain parameter to be 20, selecting superposition to be 8, selecting track spacing to be 5mm, and selecting continuous storage;
secondly, arranging measuring lines with the distance of 5-10cm in the horizontal direction and the vertical direction in a node area to be detected respectively, wherein the length of the measuring lines is not less than 1m, and the radar antenna moves at a constant speed along the measuring lines for testing, wherein the moving speed is 0.2 m/s;
thirdly, after the test is finished, processing the radar original data, extracting amplitude values corresponding to all the single waves in the whole time range after the radar original data are processed, further processing and analyzing the extracted amplitude values by using MATLAB programming, and obtaining a selection interval of target area energy and variance of four reflection echoes including steel plates, reinforcing steel bars, hollows and incompact inside the nodes on the basis of amplitude attributes, wherein the energy refers to the square sum of single-column data in a radar data matrix; the variance refers to the variance of single-row data in the radar data matrix; determining the geometric characteristic of the target body according to the intersection of the energy interval and the variance interval, and determining the dielectric property of the target body according to the sum of all amplitude absolute values in the intersection area;
and fourthly, obtaining an evaluation index of the construction quality of the complex node of the steel plate shear wall according to the geometric characteristics and the dielectric property of the target body, and evaluating the construction quality of the complex node according to the evaluation index.
Thirdly, extracting amplitude values in all time ranges, firstly calculating the sum of squares of all amplitude values on all sampling points of each channel, wherein the sum of squares of the amplitudes on all sampling points of the single-channel waveform represents the energy of the radar echo, the higher the single-channel wave energy value is, the more uneven the medium passing through the channel wave during propagation is, the greater the degree of reflection/refraction is, and the greater the intensity of the reflected wave is; and then calculating the variance of all the single-channel waves in the horizontal direction of the same sampling point in the whole time range, wherein the larger the difference is, the larger the dispersion degree of the amplitude value on the sampling point is, the representing the non-uniform degree of the medium on the depth is, and the larger the variance is, the more non-uniform the medium on the depth is.
The construction quality evaluation standard which is suitable for the complex node of the steel plate shear wall in a large range is extracted from a plurality of detection results, and the detection technology is convenient to use and popularize.
The invention has the following beneficial effects:
1. the method extracts the amplitude values of all single-channel echoes in the whole time range of the radar image, and obtains the information such as the number of reinforcing bars in the complex node of the steel plate shear wall, the distance between the reinforcing bars, the diameter of the reinforcing bars, the thickness and the number of the steel plate, whether the pouring is not compact and the like by analyzing the energy and the variance of the radar image through MATLAB programming, thereby providing scientific basis for evaluating the construction quality of the complex node of the steel plate shear wall.
2. The method provides accurate and specific important measurement parameters for the special object of the complex node of the steel plate shear wall, and radar data with higher quality and more comprehensive performance can be obtained according to the parameter setting and operation during scanning.
3. According to the invention, based on the MATLAB processing and analyzing results of the amplitude, the construction quality evaluation standard suitable for the complex node of the steel plate shear wall in a large range is summarized and summarized, and a basis is provided for the quality detection work in the engineering field in the future.
4. The method has the advantages of simple and efficient detection, convenient operation, cost saving, accurate identification, no damage, no pollution and the like, and has higher use value and popularization prospect in detecting the construction quality of the complex steel plate shear wall node.
Drawings
FIG. 1 is a flow chart of the detection method of the present invention;
FIG. 2 is a graph of raw radar data for the present invention;
FIG. 3 is a graph of processed radar data according to the present invention;
FIG. 4 is a waveform of a target reflection single trace according to the present invention;
FIG. 5 is a graph of amplitude values of a single echo in the entire time range of the present invention.
Detailed Description
A method for detecting the quality of a complex steel plate shear wall node based on ground penetrating radar scanning comprises the following steps:
firstly, a 1700MHz radar antenna is adopted, the dielectric constant is set to be 7, the time window is selected to be 10ns, the number of sampling points is set to be 512, the distance measurement mode is selected for scanning, the distance measurement wheels are 60mm, the gain parameter is set to be 20, the superposition is selected to be 8, the track spacing is 5mm, and continuous storage is selected;
secondly, arranging measuring lines with the distance of 5-10cm in the horizontal direction and the vertical direction in a node area to be detected respectively, wherein the length of the measuring lines is not less than 1m, and the radar antenna moves at a constant speed along the measuring lines for testing, wherein the moving speed is 0.2 m/s;
thirdly, after the test is finished, processing the radar original data, extracting amplitude values corresponding to all the single waves in the whole time range after the radar original data are processed, further processing and analyzing the extracted amplitude values by using MATLAB programming, and obtaining a selection interval of target area energy and variance of four reflection echoes including steel plates, reinforcing steel bars, hollows and incompact inside the nodes on the basis of amplitude attributes, wherein the energy refers to the square sum of single-column data in a radar data matrix; the variance refers to the variance of single-row data in the radar data matrix; determining the geometric characteristic of the target body according to the intersection of the energy interval and the variance interval, and determining the dielectric property of the target body according to the sum of all amplitude absolute values in the intersection area;
and fourthly, obtaining an evaluation index of the construction quality of the complex node of the steel plate shear wall according to the geometric characteristics and the dielectric property of the target body, and evaluating the construction quality of the complex node according to the evaluation index.
Thirdly, extracting amplitude values in all time ranges, firstly calculating the sum of squares of all amplitude values on all sampling points of each channel, wherein the sum of squares of the amplitudes on all sampling points of the single-channel waveform represents the energy of the radar echo, the higher the single-channel wave energy value is, the more uneven the medium passing through the channel wave during propagation is, the greater the degree of reflection/refraction is, and the greater the intensity of the reflected wave is; and then calculating the variance of all the single-channel waves in the horizontal direction of the same sampling point in the whole time range, wherein the larger the difference is, the larger the dispersion degree of the amplitude value on the sampling point is, the representing the non-uniform degree of the medium on the depth is, and the larger the variance is, the more non-uniform the medium on the depth is.
Examples
The method comprises the following steps of firstly, carrying out dust removal and decontamination treatment on the surface of a complex steel plate shear wall node, cleaning up the residual foreign matters with uneven wall surface such as pouring residues and steel bar joints, ensuring the flatness in a line measuring range, and avoiding influencing the stable movement of a radar antenna.
And measuring lines with the interval of 10cm are respectively arranged in the node area to be detected along the horizontal direction and the vertical direction.
And connecting a power supply to a node detection field, and supplying power to the computer to ensure that the computer is always in a working state.
And connecting the fully charged lithium battery with the control unit, connecting the radar antenna with the control unit in a wired manner, connecting the control unit with the computer host in a wireless manner, detecting whether the connection condition is good or not, and completing the connection work of the whole set of detection equipment.
The GeoScan32 scanning software installed on the computer is opened, whether the working state of the equipment is normal or not is checked before detection is carried out, and the measurement parameters are set after the detection is finished.
Because the thickness of the steel plate shear wall is generally not more than 700mm, the 1700MHz radar antenna is selected to have higher resolution ratio, so that the internal information of the node can be identified more clearly and accurately.
The dielectric constant of the reinforced concrete is 6-8, and the dielectric constant of the detection target body is set to be 7 during actual scanning. The track pitch was taken to be 5 mm.
For the measurement of the side face of the wall body, because the thickness direction of the wall body is provided with steel plates with uncertain intervals, the dielectric constant of the steel plates is infinite, and electromagnetic waves cannot penetrate through the steel plates, so that the side face of the wall body is not required to be set with too large time window parameters, the detection thickness and the detection precision of the wall body are considered, and the time windows of the front face, the back face and the side face of the wall body during detection are selected to be 10 ns.
After the time window parameters are determined, the number of radar sampling points is set to 512 according to the radar image precision requirement and the electromagnetic wave propagation characteristic.
The overlay setting of 8 may identify more subtle cracks and smaller hollows inside the node.
In order to enable detection to have higher detection precision and identification effect, a measuring line is selected for primary detection, radar images and waveforms obtained by scanning are preprocessed in time, the detection effect is estimated, and measurement parameters are adjusted appropriately according to analysis of the primary detection result.
After the preparation work is done, detection is formally started according to a preset detection scheme, the radar antenna is kept to move slowly and uniformly along a measuring line during detection, and when scanning of one measuring line is finished, a radar image displayed in a computer is timely checked, and if obvious human operation errors or serious interference signals exist, measurement needs to be conducted again after the factors are eliminated.
The raw radar image processing comprises the following steps:
(1) correcting the horizontal distance of the image, calling a waveform attribute dialog box, inputting a real distance obtained by actual measurement at a signal position away from a starting point, sequentially clicking position resetting and calculating positions, and then clicking application and determining;
(2) correcting the zero position of the single-channel waveform, calling a waveform attribute dialog box, and clicking pp;
(3) removing an air layer from the corrected waveform, selecting a point with the maximum amplitude value of the first wave, namely a first wave peak, selecting the upper part of the point as the air layer, clicking for editing, and selecting to cut off an upper signal;
(4) resetting the image starting position, calling out a file header dialog box, setting the antenna base to be 1, and setting the image starting position to be 0;
(5) carrying out distortion removal processing on the image, extracting average channels, carrying out moving average calculation on each value of each channel in the whole time range, and subtracting the moving average value from an actual value to remove the amplitude offset of the deep signal;
(6) performing gain processing on the image subjected to distortion removal processing, pulling a gain bar, and observing the change condition of the radar image to obtain an optimal gain value;
(7) the mean-difference subtraction processing is carried out, the mean value of the same sampling point of each waveform is subtracted at the same time, the energy carried by all waveforms is reduced, and meanwhile, the variance information in the waveforms is not influenced;
(8) and smoothing, namely performing noise suppression on the partial channel number waveform with high energy.
And further processing and analyzing the radar data after the processing, and deducing the geometric characteristics and the dielectric properties of the abnormal reflection region.
The steps for processing the amplitude values using MATLAB programming are as follows:
(1) extracting waveform amplitude data of all tracks of the processed radar image;
(2) calculating the energy of each channel and the variance of the same sampling point among all channels according to the extracted waveform amplitude data;
(3) respectively finding out a determination interval of the numerical distribution with larger energy and variance in the step (2) by adopting a probability distribution function, wherein the normalized energy interval of the steel plate is (0.80, 1), the normalized energy interval of the steel bar is (0.82, 1), the normalized energy interval of the empty drum is (0.76, 1), and the normalized energy interval of the non-compact area is (0.64, 1); the normalized variance interval of the steel plate is (0.81, 1), the normalized variance interval of the steel bar is (0.84, 1), the normalized variance interval of the empty drum is (0.73, 1), and the normalized variance interval of the non-compact area is (0.59, 1).
(4) Screening out columns corresponding to the energy intervals and rows corresponding to the variance intervals according to the large energy value intervals and the large variance intervals determined in the step (3), and finding out all waveform amplitude data on the intersection of the columns and the rows, wherein the intersection of the two waveform amplitude data is a reflection abnormal area;
(5) solving the sum of all amplitude absolute values on the intersection of the energy interval and the variance interval determined in the step (4);
(6) and (5) deducing the dielectric property of the abnormal region according to the sum of the absolute values of the amplitudes of the abnormal region obtained in the step (5), and qualitatively obtaining the property of the abnormal region by combining the embedding depth of the region and the node reinforcement map.
And summarizing and concluding a construction quality evaluation standard which is suitable for the complex node of the steel plate shear wall in a large range based on the processing and analyzing result of the MATLAB on the amplitude, and providing a basis for the quality detection work in the engineering field.
Claims (1)
1. A method for detecting the quality of a complex steel plate shear wall node based on ground penetrating radar scanning is characterized by comprising the following steps: the method comprises the following steps:
firstly, adopting a 1700Hz radar antenna, setting the dielectric constant to be 7, selecting 10ns for a time window, setting the number of sampling points to be 512, selecting a ranging mode to scan, setting the distance between ranging wheels to be 60mm, setting the gain parameter to be 20, selecting superposition to be 8, selecting track spacing to be 5mm, and selecting continuous storage;
secondly, arranging measuring lines with the distance of 5-10cm in the horizontal direction and the vertical direction in a node area to be detected respectively, wherein the length of the measuring lines is not less than 1m, and the radar antenna moves at a constant speed along the measuring lines for testing, wherein the moving speed is 0.2 m/s;
thirdly, after the test is finished, processing the radar original data, extracting amplitude values corresponding to all the single waves in the whole time range after the radar original data are processed, further processing and analyzing the extracted amplitude values by using MATLAB programming, and obtaining a selection interval of target area energy and variance of four reflection echoes including steel plates, reinforcing steel bars, hollows and incompact inside the nodes on the basis of amplitude attributes, wherein the energy refers to the square sum of single-column data in a radar data matrix; the variance refers to the variance of single-row data in the radar data matrix; determining the geometric characteristic of the target body according to the intersection of the energy interval and the variance interval, and determining the dielectric property of the target body according to the sum of all amplitude absolute values in the intersection area;
wherein, the amplitude values corresponding to all the single channels in the whole time range are extracted by the following method: firstly, calculating the sum of squares of all amplitude values on all sampling points of each path, wherein the sum of squares of the amplitudes on all sampling points of a single-path waveform represents the energy of a radar echo, the higher the single-path wave energy value is, the more uneven a medium passing through the path of wave during propagation is, the greater the degree of reflection/refraction is, and the greater the intensity of a reflected wave is; then calculating the variance of all the single-channel waves in the same sampling point in the horizontal direction in the whole time range, wherein the larger the difference is, the larger the dispersion degree of the amplitude value on the sampling point is, the representing the non-uniform degree of the medium on the depth is, and the larger the variance is, the more non-uniform the medium on the depth is;
and fourthly, obtaining an evaluation index of the construction quality of the complex node of the steel plate shear wall according to the geometric characteristics and the dielectric property of the target body, and evaluating the construction quality of the complex node according to the evaluation index.
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